There's no getting away from it: the menopause is a perfectly normal life change and every woman will experience it. Dr Lesley Hickin looks at the signs and symptoms.

Everyone reacts to the menopause in different ways, so you need to know what to expect in order to help yourself to stay healthy and happy and to know what treatment and lifestyle changes could be of benefit to you. The menopause is not something to fear - although some women dread reaching it, others look on it as a new lease on life physically, emotionally, sexually and spiritually.

What is the menopause?
The precise definition of the menopause is the time when your periods stop permanently, recognised retrospectively after an absence of periods for 12 months. This happens to most women between the age of 40 and 58, with an average age of 51.4 years. A few women reach their menopause in their thirties (before 40 this is called premature menopause and can be induced surgically or by drug treatment), and a smaller number don't reach menopause until they are 60.

When will it happen to me?
There are several things influencing the timing of the menopause in individual women. When your mother and grandmother went through their menopause influences the timing of yours. Factors influencing the possibility of an earlier menopause include having no children and being a smoker (smoking may make it happen two years earlier). Childhood treatment of cancer, with radiation to the pelvis or chemotherapy, may also bring on an early menopause.

What is the perimenopause?
During the years leading up to the time when your periods stop, you may notice changes occurring to your body. These carry on for some time after the menopause as well. So when we talk of 'going through the change of life' we are describing an ongoing process rather than a sudden event. This time is technically known as the perimenopause, and it usually lasts for about four years. The changes happen as the ovaries' production of oestrogen slows down, with hormone levels yo-yoing just as they did in adolescence.

It is not easy to diagnose the perimenopause using blood tests because your hormone levels can yo-yo about for several years before periods finish. After your last period there are two hormones commonly used to indicate that it has happened - LH and FSH. These are very high once oestrogen levels are low. Menopausal symptoms are caused by changes in levels of oestrogen, mainly produced by your ovaries but some is made in fatty tissue and the adrenal glands.

Changes to your menstrual cycle
Only about 10 per cent of women stop menstruating suddenly. You may have irregular bleeding for some time before periods stop altogether, and you may notice more or less frequent bleeds. These bleeds may be heavier or lighter than you have previously experienced; you may be worried that there is another cause for the changes in your periods so do not hesitate to seek medical advice.

Common symptoms
Around 75 per cent of women experience hot flushes, night sweats and heat intolerance and these can predate the menopause. In most cases they settle in a couple of years but women can experience hot flushes for many years. They are often the reason for seeking treatment with HRT, which is extremely effective at relieving this problem.

Hot flushes are associated with sudden hormone changes in the bloodstream, and may give you a feeling of gentle warmth or sudden severe bursts of heat and drenching sweats. Flushes can last from a few seconds to several minutes and are particularly distressing at night when they may add to insomnia caused by other reasons.

Common psychological and emotional symptoms are irritability, a changed sleeping pattern and mood swings, sometimes leading to an episode of clinical depression. These symptoms may have more to do with other changes in your life - some women mourn the loss of fertility and feel unattractive.

Menopause complications
Reduction in oestrogen levels is one of the causes of osteoporosis, putting women at risk of bone fractures in later life. There are no symptoms in the early stages so you should be aware of things that may increase your risk of developing it and what you can do to prevent bone density loss. These include regular exercise, non-smoking, high calcium and vitamin D diets and taking HRT if you are suitable. Other non-hormonal drugs are available nowadays for osteoporosis prevention, and the condition can be identified by a special X-ray of your hip and back called a DEXA scan.

Vaginal and urinary symptoms
Reduced levels of oestrogen cause thinning of the membrane lining the vagina plus problems with dryness. Similar changes occur in the urethra and you may experience leaking of urine, difficulty in passing urine and needing to empty your bladder more frequently, particularly at night. These problems respond well to HRT taken by mouth or applied locally as a cream.